The present disclosure herein relates generally to packaging of fluid compositions, e.g., paint and paint related products such as solvent-based paints and water-based paints. More particularly, the disclosure herein pertains to interior portions of containers, e.g., interior portions of lids of containers, used to hold such fluid compositions that reduce skinning.
Premature drying of compositions, e.g., paints, inside of packaging is problematic. Premature drying in packaging refers to the drying (and/or curing) of compositions inside packaging, resulting in hard particles (e.g., “skins”) or at least undesirable thickening of the compositions (e.g., paint formulations) in the packaging. Such drying may be caused by factors such as increased temperature, change in temperature, and the amount of or the humidity of the air trapped inside the packaging.
Skinning refers to a specific form of premature drying where a coherent layer of a fluid composition (e.g., such as a thin layer of paint at the underside of a paint container lid) undergoes premature drying on one or more surfaces inside a package (e.g., a container, such as a 0.5, 1.0, or 2 liter paint container). Such premature drying may occur in, for example, water-based paints due to coagulation, a process in which some or all of the water and solvents evaporate and the binder particles in the paint fuse together irreversibly bound into network structures. Further, for example, premature drying may occur in solvent-based paints due to the uptake of oxygen leading to the oxidative cross-linking of the paint.
Various concepts have been discussed which attempt to prevent skinning. For example, a thin film of water or other protecting fluid on the bulk fluid in the container has been suggested for use to prevent skinning, as well as using coatings on the surfaces upon which the premature dried layer is expected to form. Further, other solutions to the skinning problem include attempting to prevent the skin which has formed from breaking off and ending up in the bulk product (e.g., bulk paint in the container). For example, use of a sharp edge on the lid that cuts the skin when the container is opened has been described.
Still further, as best understood, U.S. Patent Application Publication No. 2004/0062894 A1, published Apr. 1, 2004, entitled “Method of Packaging Solvent or Water Based Formulations to Reduce Skinning,” describes a container, which is adapted to contain a water based or solvent based formulation. It is suggested that the container include a container sealing means, such as a lid, including an anti-skinning layer located on at least a portion of the internal surface thereof. The anti-skinning layer is alleged to be capable of retaining a layer of the formulation without excluding the formulation vapor in the container from contacting the formulation. Further, it is alleged that the anti-skinning layer substantially maintains the water or solvent concentration of a portion of the formulation retained on the anti-skinning layer (e.g., allegedly to prevent skinning). The anti-skinning layer described therein further is alleged to have insulative properties, e.g., to reduce the temperature differential that occurs between the lid and the body of paint or formulation.
However, there is always a need to provide alternate and/or improved techniques to prevent skinning.